QE432 : Petrology, Geochemistry and Tectonic Seting of Permian Alkaline Basic Magmatism in Baladeh Area, Central Alborz
Thesis > Central Library of Shahrood University > Geosciences > MSc > 2019
Authors:
Hadigheh Khatoon Kazemi [Author], Habibolah Ghasemi[Supervisor], Aziziollah Taheri[Advisor]
Abstarct: The Permian rock sequence includes formations of Durod (mainly of sandstone and shale) with the lower Permian Age and the fluvial-Deltaic environment, Ruteh (mainly of limestone with marl interlaxyers) with the middle Permian age and the carbonate platform environment and Nesen (mainly of limestone and shale) with the Upper Permian age and carbonate platform (lagoon, barrier and open marine) environment, is located near the Amol city, Mazandaran Provine in the northern part of the central Alborz mountains,contains mafic igneous rocks including basalt, microgabbro and Lamprophyre. These rocks are as intrusive bodies (microgabbro, lamprophyre) within the Dorud Formation and the lower part of the Ruteh Formation, and are in the form of extrusive (basalt) and pyroclastics in the upper part of the Ruteh Formation. They show porphyry, microlitic porphyry, hyalomicrolitic porphyry, glomeroporphyry, sieve, intersertal, trachytic, amigdaloidal, ophitic, subophitic, poikilitic, granular and intergranular textures. Feldspar and clinopyroxene in the basalts and gabbros and amphibole in the lamprophyres are the main constituents minerals of these rocks. Feldspars composition in basalts are in the range of andesine-labradorite and in gabbros are in the range of labradorite, oligoclase and albite and in the lamprophyres are in the range of anorthoclase, oligoclase and albite. Clinopyroxenes are iron-magnesium-calcium end-member and free of sodium. The clinopyroxene composition in basalts and gabbros is in the range of diopside- augite and a small number are within the range of pigeonite and in the lamprophyres are in the diopside- augite range. Amphiboles are from the calcic type and include kersotite, pargasite, edenite, tchermakite and magnesium hastingsite. These rocks show enrichment in light-rare earth elements (LREE) and depletion in heavy rare earth elements (HREE) in chondrite normalized diagrams. In the multi-elements spidergrams normalized to the primary mantle they show a high concentration of large ion lithophile elements (LILE) and a low concentration of high field strength elements (HFSE) and depletion in K, Nb and Zr. In the different discrimination tectonic diagrams, these rocks plot in the intra-continental rift environment with the characteristics of the mantle source of the oceanic island basalts. The magma forming of these rocks was originated from <20% partial melting of a spinel-garnet lherzolite at depths of 90-110 km and spontaneously with the Permian extensional phase governed on the southern edge of the Paleotethys oceanic basin in the Alborz ascended and replaced in the Permian rock sequence.
Keywords:
#Basalt #Gabbro #Lamprophyre #Permian #Central Alborz #Balade #Paleotethys. Link
Keeping place: Central Library of Shahrood University
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